A Way Out

The pros and cons of exit device technology

• By Shawn Mahoney
• Feb 29, 2008

They may not be as cutting edge as video analytics and other new security breakthroughs— but every building has them. And knowing which type of exit device to use and where to implement it is key to employee and customer security.

Exit devices began as a simple but effective idea in life-saving door hardware. Carl Prinzler conceived them in response to deaths caused by blocked doors at the tragic 1903 Iroquois Theater fire in Chicago. They were introduced in 1908 through Vonnegut Hardware. With these devices, a door finally could be locked from the outside while remaining unlocked inside.

Two types of exit devices are available today—panic hardware and fire-rated exit hardware. Panic hardware is used on openings to allow people to get out of a building in a fire or other panic situation, but firerated hardware must be used on fire-rated openings. While both types are UL listed for accident hazards, only fire-rated devices are capable of keeping a door latched for a specified period of time during an actual fire.

What follows are the major developments in exit devices and ways in which their features can be combined to meet ever-changing life safety, security and accessibility requirements.

An Old Classic
The first exit devices are still common and seen in just about any major building: horizontal bars. This horizontal rod or bar is suspended between the device’s hinge and lock case. When pushed, the bar releases the latch and allows the door to be opened from inside while it remains locked from the outside. Pushing anywhere across the bar will activate it. This has proved to be important where crowds could block a door in an emergency, giving rise to the familiar term “panic bars” for these devices.

The basic design, with minor improvements, is still used today. The Von Duprin 88 series provides a suitable combination of fire and life safety and security protection at places like schools and movie theaters, where the basic need is to keep the door locked from the outside while allowing it to open from inside. Also, some architects prefer bars’ appearance.

Horizontal bars offer several latching options. Some have vertical rods that provide a better distribution of latching force around the opening. Mortise devices and concealed vertical rods also can be selected to improve appearance and prevent rod damage.

New Possibilities
In 1972, Von Duprin introduced its 33 series, a pushpad exit device that represented a radical departure from the old, traditional exit device design. Its smoother, more modern appearance was designed to complement a variety of architecture. At the same time, its unique rectangular body, attached to the door, provided the potential for electrified latch control and monitoring.

This device was designed to fit narrowstile doors and was followed in 1980 by the familiar 99 series device for standard stile widths. Today, most manufacturers offer similar types of pushpad devices, and new variations of electronic control continue to be developed.

As with the original crossbar devices, latching mechanisms for pushpad devices soon became available in mortise, vertical rod and concealed vertical rod designs. For applications where carts or gurneys posed a risk for damaging vertical rods, manufacturers began to offer devices with only a top rod.

By electrifying these devices, security managers could provide safe egress and maintain a high level of security. All too often, someone holding the door open can compromise security. With electrified exit devices, security integrators and managers can add alarm horns, door position switches and remote monitoring signals to manage such situations.

Another popular option is electric latch retraction. This makes a new range of functions possible, including remote dogging to convert a door to push/pull operation, instant relatching of multiple doors in emergency situations and electronic credential access control.

When teamed with automatic door operators, electrified exit devices play a major role in maintaining security while meeting the guidelines of the Americans with Disabilities Act. Whether operated by a bollard- or wall-mounted switch or by an electronic access credential, the latch must retract before the door can be opened, unless it is dogged down. In applications where the outer and inner doors must open and close in order, such as in vestibules, the latch can be controlled to retract in sequence before the operator opens the door.

Expanded Options
The next big step in resolving the life safety versus security dilemma was the introduction of the delayed egress exit device. It sounds an alarm and delays a person from exiting for a code-regulated 15 seconds. This not only discourages unauthorized use but also provides an opportunity for a security response. In an emergency, when the building’s fire alarm or sprinkler system is activated, these devices automatically disable to allow immediate egress.

Moving up the security ladder, Von Duprin’s Chexit™ represented a new code category known as special locking arrangements. This self-contained system incorporates all controls, auxiliary locking, local alarm and remote signaling output. Arming and disarming are done with a key cylinder located on the front of the device. An LED indicator shows the status of the device under all lighting conditions.

Such devices are ideal for tightly controlled areas such as computer rooms, research and development labs or classified security facilities. Other applications include retail establishments. Delayed egress devices also are popular in shopping malls, where secluded fire exits and a common corridor let people escape quickly. Another important use is in hospital nurseries, especially when teamed with proximity loops built into door frames that sense RFID chips used to prevent kidnappings.

Recessed exit devices were developed to meet California Office of Statewide Health Planning and Development requirements that mandated a 44-inch minimum clear width for cross-corridor fire door openings in hospitals. To avoid constructing deep pockets or wider corridors, manufacturers have developed exit devices in which the mechanism is contained primarily within the door itself. The only part that protrudes is the touchpad, which may extend about an inch or less in the retracted position.

While the ability to achieve clear-width openings is one of the practical benefits of a recessed device, there are several other advantages. Aesthetically, when a long corridor contains several pair of cross-corridor doors, the recessed devices do not protrude into the visual line and yield a cleaner looking building design. Yet, they fulfill the code requirements for panic or fire exit devices.

More Strength
Popular pushpad exit devices long have been used to provide a practical combination of mechanical security and fire/life safety for a broad range of applications in public buildings. However, where security needs are greater, pushpad latching mechanisms may not provide sufficient protection against strong-arm techniques.

A new development combines the traditional convenience of these devices with the added strength of an innovative latching concept. The Von Duprin XP 98/99 Rim exit device features a patented center case design that builds upon the 98/99 series and adds an innovative latching concept.

This two-piece latch bolt forms a 90- degree latch to the strike’s contact. The latch bolt and strike design collaborate to ensure the highest level of door opening security. Useful for door openings subject to violent “pull force” attack, this design delivers more than 2,000 pounds of static load force resistance. The device also requires less pressure to unlatch. This makes it more suitable for meeting ADA guidelines and making doors easier to open for the elderly and young.

To facilitate the installation process, the rim device matches the existing 98/99 rim device footprint, eliminating costly doorprep changes. Thus, it supports quick installation to a door opening that has suffered the effects of violent door attacks or years of deteriorating door or frame conditions. Importantly, the new device conforms to ANSI/BHMA 156.3 criteria and UL panic and fire listings currently held by the standard 98/99 rim device.

The trend in exit device development has followed mechanical and electrical innovation, responding to the continually changing needs of security and life safety. Manufacturers will maintain their commitment to meeting new and existing needs in these critical areas with continued development and testing. It is up to security directors and their integrators to ensure the right exit device is used on each and every door.